Update Dockerfile to include local-extract
Update Dockerfile to include local-extract

This component is required to use the On-Demand Scanning API (http://cloud/container-analysis/docs/on-demand-scanning). Including it in this builder allows users to run a scan as a Cloud Build step without having to install local-extract themselves.
google-octo/cloud-builders,GoogleCloudPlatform/cloud-builders,google-octo/cloud-builders,GoogleCloudPlatform/cloud-builders,google-octo/cloud-builders,GoogleCloudPlatform/cloud-builders,google-octo/cloud-builders,GoogleCloudPlatform/cloud-builders,GoogleCloudPlatform/cloud-builders,google-octo/cloud-builders,google-octo/cloud-builders,google-octo/cloud-builders,GoogleCloudPlatform/cloud-builders,GoogleCloudPlatform/cloud-builders